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Post by oldgeek on Aug 13, 2024 17:20:36 GMT -5
Time to build another motor! Hope this one is even better   |
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Post by oldgeek on Aug 14, 2024 17:50:28 GMT -5
I keep forgetting just how much has to be done to these cases to build a large displacement motor. So far I have deepened the 4 cylinder studs holes by 14mm and tapped the bottom of them to 6mm. Drilled the 3 carter bolt holes (that get opened up when you cut the crank area) all the way through the large half of the cases and tapped them to 6mm for the studs that will be installed. Cut the throat in the cases using the router and template so the larger cylinder will fit. Clearanced the crank area so the larger crank will fit. pictureOpened up the intake port windows and intake path with the dremel. picture Undercut the oil passage with the dremel so the epoxy will have something to help lock it in place. Cut the area in the cases above the crank where the piston bottoms out at BDC. Cut 3ea 6mm 90mm long stainless all thread studs for the carters. Cut in a boost port. pictureMore work on the intake path. pictureMatched transfers on cases to cylinder. pictureTrimmed cylinder skirt for better flow. Filled some dead space in crank area of cases with epoxy. pictureReplaced all bearings in the gearbox, checked fitment and took it back apart to prepare for motor assembly. I will list other steps in this post as they get done. I have also been test fitting cylinders. I have the LC 54mm Taida that I modified that was on this motor before the gearbox broke, another spare Taida cylinder that has not been modified, and a cool looking 54.5 LC Vastro brand (Thanks oldskool )that I will post some pictures of at some point. The exhaust port on the Vastro is round and sporty compared to the ex port on the Taida. All of these cylinders are challenging to seal at the cylinder base due to small amount of sealing area you are left with. I dont know if it is a Kymco only problem or if the Hondas also have the same problem.    |
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Post by 90GTVert on Aug 14, 2024 22:43:30 GMT -5
a cool looking 54.5 LC Vastro brand (Thanks oldskool )that I will post some pictures of at some point. The exhaust port on the Vastro is round and sporty compared to the ex port on the Taida. The guy that I've cut too many Honda cases for uses some Vastro stuff. He's originally from the Dominican Republic and says it's their brand. He buys everything from there regardless of what I tell him. They also sell him TWH which I've used cranks from more than a few times. It looks to me like he's just getting Chinese and Taiwan parts and Vastro is on Tunescoot/AliExpress. Anyway, the Vastro cylinder that he brought over looked pretty good. It was nothing special, but durations would be good if he had a real racing pipe (195/135 or something like that) and he always uses a 1mm base spacer. I told him it would be nice to have a pipe that makes power at maybe 12k with those durations. He says it does rev really high, but he has no tach. Not sure he understands how rare a cast iron 125cc at 12,000RPM with unmodified Taiwan parts, stock ignition with a Chinese CDI and some gold plated unknown pipe is. Either with the TPR 86 or the RC1, I'm gonna find out what's it's all about in the name of science. |
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Post by oldgeek on Aug 15, 2024 1:01:01 GMT -5
The guy that I've cut too many Honda cases for uses some Vastro stuff. He's originally from the Dominican Republic and says it's their brand. He buys everything from there regardless of what I tell him. They also sell him TWH which I've used cranks from more than a few times. It looks to me like he's just getting Chinese and Taiwan parts and Vastro is on Tunescoot/AliExpress. Anyway, the Vastro cylinder that he brought over looked pretty good. It was nothing special, but durations would be good if he had a real racing pipe (195/135 or something like that) and he always uses a 1mm base spacer. I told him it would be nice to have a pipe that makes power at maybe 12k with those durations. He says it does rev really high, but he has no tach. Not sure he understands how rare a cast iron 125cc at 12,000RPM with unmodified Taiwan parts, stock ignition with a Chinese CDI and some gold plated unknown pipe is. Either with the TPR 86 or the RC1, I'm gonna find out what's it's all about in the name of science. Half of me just wants to slap it all together and send it, the other half of me wants to do more, at least CC it to know where it is. The Vastro cylinder did seem to set up better right out of the box. I have not checked durations yet, but by the looks of the tall transfers 195/135 sounds about right. I bet he uses the 1mm spacer to help seal the base, because you end up with 3-3.5mm sealing surfaces on the case and the cylinder at the transfer ducts and they do not even match up! I have a Taida AC 54mm, I checked how it set up. It seems to want a crank with a little less stroke than the 52.6's that I have. I can't see going back to an AC cylinder now that I have been on the LC team. LOL |
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Post by 90GTVert on Aug 15, 2024 5:38:55 GMT -5
I bet he uses the 1mm spacer to help seal the base, because you end up with 3-3.5mm sealing surfaces on the case and the cylinder at the transfer ducts and they do not even match up! For his with 52mm stroke, the 1mm spacer makes the floors align at BDC and actually gave him 0.8mm squish. I was surprised how well it worked out. I can't see going back to an AC cylinder now that I have been on the LC team. LOL From the Mina/RC, I agree. When it's decent stuff that will seal, it makes nicer setups. The Taiwan Minarelli stuff that I had didn't like to stay sealed and that was miserable. |
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Post by oldgeek on Aug 15, 2024 19:50:13 GMT -5
Checked durations on a couple cylinders today.  The new Taida Exhaust 191 / Transfers 129 Piston top is 15° below transfer floor at BDC  The Vastro cylinder surprised me, Exhaust 194 / Transfers 139 Piston top is even with transfers floor at BDC  The Taida cylinder that I cut the base on. Exhaust 189 / Transfers 126 Piston top is even with transfer floor at BDC. Apparently durations ended up rather tame after all was said and done. If I use this cylinder I could add some duration to the exhaust. The new unmodified taida cylinder has the piston top below the transfers at BDC, if I fix that it will end up basically like the one I already modified. The Vastro cylinder has long transfer duration, would the long transfer duration assist in filling the cylinder through the poor transfer ducts? The exhaust duration is already pretty good on this cylinder. |
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Post by 190mech on Aug 16, 2024 3:47:18 GMT -5
139 is a bit high, may get some exhaust backwash but it is worth a test run anyhow. How does the piston top look at TDC? That looks like an AC converted to LC in the pic..
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Post by oldgeek on Aug 16, 2024 5:55:32 GMT -5
139 is a bit high, may get some exhaust backwash but it is worth a test run anyhow. How does the piston top look at TDC? That looks like an AC converted to LC in the pic.. At TDC the piston looks great, I should be able to get the squish anywhere I want. Yes, it is an AC converted to LC. They broke two rows of fins out and looks like silicone braze welded a water jacket up. Another thing I like about the Vastro is the piston skirt, It is much longer than the Taida piston and I had to clearance the cases out so the piston would not hit at BDC. Consequently the Vastro piston covers the exhaust port much better at TDC than the Taida setup does. I have another question. How important is the boost port on these motors? The stock Kymco cases have a very small boost port channel. After modifying the cases for the larger cylinder the boost port is gone. I usually cut it open to match the port size in the cylinder but was wondering if it really helps or just adds possibly unwanted case volume? |
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Post by 190mech on Aug 16, 2024 19:00:41 GMT -5
The boost port (C) is quite small on the latest high power engines, it acts as a flow director for the larger A and B ports to carry their flow upward towards the combustion chamber. Would it be possible to cut a hole in the cylinder barrel and a matching one in the piston skirt to get the mixture into the C port?
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Post by 808ministroke on Aug 16, 2024 19:52:05 GMT -5
The boost port (C) is quite small on the latest high power engines, it acts as a flow director for the larger A and B ports to carry their flow upward towards the combustion chamber. Would it be possible to cut a hole in the cylinder barrel and a matching one in the piston skirt to get the mixture into the C port? So is this the true reason for windowed pistons? Or are windows for lubrication of the small and bearing and pistons with a cut out at the very bottom are for this purpose to allow mixture through the boostport? I always thought that the boost port was simply another transfer port and therefore just as important as the ANB transfers, In my cylinder MHR86, There is a total of 3 ports in the boost section I always assumed more boost ports or area was beneficial for high RPM |
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Post by 190mech on Aug 17, 2024 16:24:09 GMT -5
It was used a long while back to add another port to 2 duct engines, A G Bell's book has reference to them (page 29 & 47), Jennings also (page 65 & 68).They did have a timed window cut into the piston to feed the boost port. Later engines had a cast in port that feeds directly from the case, I was just trying to help Scott find a way to feed the C port without digging into already thin cases!
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Post by oldgeek on Aug 17, 2024 17:55:06 GMT -5
It was used a long while back to add another port to 2 duct engines, A G Bell's book has reference to them (page 29 & 47), Jennings also (page 65 & 68).They did have a timed window cut into the piston to feed the boost port. Later engines had a cast in port that feeds directly from the case, I was just trying to help Scott find a way to feed the C port without digging into already thin cases! Thanks for the info, I really should read up on these things. The area where the boost port is in the Kymco cases has plenty of room to be opened up without causing sealing issues. I was just wondering if the boost port was really beneficial, I understand now that it is. I will get the boost port opened up to match the cylinder. I did some more setup checks with the Vastro today. A 1mm base spacer will set things up just right and puts squish around .7mm without a head gasket. I keep forgetting to take a picture of the head and the combustion chamber, Ill do that tomorrow. I pulled the water jacket cover off of the head today and was surprised to find there was no gasket or o ring groove. I will likely just seal it up with some RTV during final assembly. Also the combustion chamber in the head looks smallish to me, but I doubt I will mess with enlarging it without trying it as is first. |
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Post by oldgeek on Aug 20, 2024 16:44:53 GMT -5
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Post by 190mech on Aug 21, 2024 3:23:04 GMT -5
It sure is purdy though!!  |
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Post by aeroxbud on Aug 22, 2024 5:57:26 GMT -5
Let's hope it goes as well as it looks. 👍
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